NCLEX Review Guide: Prostaglandins in Maternity Care

Pharmacological Classification and Mechanism

• Prostaglandins are hormone-like lipid compounds derived from arachidonic acid that act as potent biological mediators affecting multiple physiological processes. They function by binding to specific G-protein-coupled receptors, triggering intracellular signaling cascades that ultimately result in their physiological effects including uterine contraction, cervical ripening, and vascular changes.
• In obstetrics, prostaglandins (primarily PGE1 and PGE2) are used to promote cervical ripening and induce labor by increasing the ground substance of collagen and increasing the activity of collagenase in the cervix, while simultaneously stimulating uterine contractions.

Dinoprostone (Cervidil, Prepidil)

• Dinoprostone is a synthetic PGE2 analog available as a vaginal insert (Cervidil) or endocervical gel (Prepidil) used for cervical ripening in pregnant women at or near term. The vaginal insert contains 10 mg of dinoprostone in a controlled-release formulation that releases approximately 0.3 mg/hour over 12 hours.
• After administration, dinoprostone gradually softens and dilates the cervix while initiating mild uterine contractions. The advantage of Cervidil is that it can be removed quickly if hyperstimulation occurs, making it preferable in certain high-risk situations.

Misoprostol (Cytotec)

• Misoprostol is a synthetic PGE1 analog originally approved for prevention of gastric ulcers but widely used off-label for cervical ripening and labor induction. It's typically administered in doses of 25-50 mcg vaginally or orally every 3-6 hours.
• Compared to dinoprostone, misoprostol is significantly less expensive, stable at room temperature, and can be administered through multiple routes (oral, vaginal, sublingual, or buccal). However, it carries a higher risk of uterine hyperstimulation and cannot be quickly removed once administered.

Labor Induction

• Prostaglandins are a first-line agent for labor induction when the cervix is unfavorable (Bishop score ≤6). They effectively ripen the cervix while simultaneously stimulating uterine contractions, often eliminating the need for separate ripening and induction agents.
• The success of prostaglandin induction is influenced by parity, gestational age, cervical status, and fetal size. Nulliparous women with an unripe cervix typically require higher doses or longer exposure than multiparous women with partially dilated cervices.

Postpartum Hemorrhage Management

• Prostaglandin analogs, particularly misoprostol (800-1000 mcg rectally), are used as second-line agents for postpartum hemorrhage when oxytocin and ergot alkaloids fail to adequately control bleeding. They cause sustained uterine contractions that help compress bleeding vessels at the placental site.
• Prostaglandin F2α (carboprost, Hemabate) is administered intramuscularly in 250 mcg doses every 15-90 minutes (maximum 8 doses) for refractory postpartum hemorrhage. It is particularly effective for hemorrhage caused by uterine atony but contraindicated in women with asthma due to its bronchoconstrictive effects.

Pregnancy Termination

• Prostaglandins are effective for terminating pregnancy at various gestational ages. Misoprostol is commonly used in combination with mifepristone for medical abortion in the first trimester, while higher doses may be used for second-trimester terminations.
• For management of missed abortion or intrauterine fetal demise, prostaglandins help induce uterine contractions to expel the products of conception, reducing the need for surgical intervention.

Assessment and Monitoring

• Prior to prostaglandin administration, perform a comprehensive assessment including vital signs, fetal heart rate pattern, contraction frequency and intensity, and cervical status. Document the initial Bishop score to serve as a baseline for evaluating effectiveness.
• During prostaglandin therapy, continuous electronic fetal monitoring is required to detect signs of fetal distress or uterine hyperstimulation. Monitor maternal vital signs every 1-2 hours, with special attention to temperature as prostaglandins can cause fever as a side effect.

Adverse Effects and Complications

• Common maternal side effects include nausea, vomiting, diarrhea, fever, and chills due to prostaglandins' systemic effects. These symptoms are typically self-limiting and can be managed with supportive care.
• The most serious complication is uterine hyperstimulation with or without fetal heart rate changes, which occurs in approximately 1-5% of patients. This requires immediate intervention including removal of the prostaglandin (if possible), lateral positioning, oxygen administration, and tocolytic therapy if needed.

Contraindications and Precautions

• Absolute contraindications to prostaglandin use include: previous uterine surgery (classical cesarean section, myomectomy), placenta previa or unexplained vaginal bleeding, active genital herpes, and hypersensitivity to prostaglandins.
• Relative contraindications include: previous low transverse cesarean delivery, grand multiparity (≥5 previous births), multiple gestation, polyhydramnios, and severe asthma (for carboprost specifically). These conditions increase the risk of uterine rupture or other complications.

Essential Knowledge for NCLEX

• Prostaglandins (PGE1 and PGE2) are primary agents for cervical ripening and labor induction, working through dual mechanisms of cervical softening and uterine stimulation.
• The two main prostaglandins used in obstetrics are dinoprostone (PGE2) and misoprostol (PGE1), each with distinct advantages and limitations regarding cost, storage, administration routes, and safety profiles.
• Clinical applications extend beyond labor induction to include management of postpartum hemorrhage (particularly carboprost/Hemabate) and pregnancy termination at various gestational ages.
• Nursing responsibilities include thorough pre-administration assessment, continuous fetal and maternal monitoring, recognition and management of complications (especially uterine hyperstimulation), and understanding contraindications.

Prostaglandins vs. Oxytocin

Dinoprostone vs. Misoprostol

Focus Areas for NCLEX

• Concentrate on understanding the nursing responsibilities related to prostaglandin administration, including pre-administration assessment, monitoring during therapy, and emergency interventions for complications.
• Know the contraindications to prostaglandin use, especially absolute contraindications like previous uterine surgery, as these are frequent test topics.
• Be familiar with the differences between prostaglandin types (dinoprostone vs. misoprostol) and their specific indications, routes, and precautions.